Sodium Citrate Salts Research Articles

Functionality of milk protein concentrate 80 with emulsifying salts and its applications in analogue cheeses

ABSTRACTMilk protein concentrate 80 (MPC80) was prepared with different emulsifying salts (ES). The effects on particle size (D50), solubility, and surface hydrophobicity (H0) of MPC80 were then observed after production. The molecular weight and secondary structure of MPC80 protein were also investigated through sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier Transform Infrared (FTIR) spectrometry. Particle size (D50) was reduced from 31.37 to 20.67 μm following the addition of sodium phosphate (SPS). The solubility of MPC80 fortified with sodium citrate salt (SCS), SPS, and sodium pyrophosphate (SPP) was improved by 80.32, 78.23, and 55.80%, respectively. The SDS-PAGE pattern showed no significant difference between the control and single-ES-fortified samples, but major protein bands (αs-CN, β-CN, κ-CN, BSA, and β-LG) had a stronger intensity than binary-ES-fortified MPC80. The FTIR results showed that the β-sheet content of ES-fortified MPC80 was relatively higher than that in the control. Compared with analogue cheeses made by MPC80 with and without ES, SCS–SPP (92:8)-modified MPC80 presented a better fluid mass and homogeneous colour.

Interference of salts used on aqueous two-phase systems on the quantification of total proteins

In this study the interference of potassium phosphate, sodium citrate, sodium chloride and sodium nitrate salts on protein quantification by Bradford's method was assessed. Potassium phosphate and sodium citrate salts are commonly used in aqueous two-phase systems for enzyme purification. Results showed that the presence of potassium phosphate and sodium citrate salts increase the absorbance of the samples, when compared with the samples without any salt. The increase in absorptivity of the solution induces errors on protein quantification, which are propagated to the calculations of specific enzyme activity and consequently on purification factor. The presence of sodium chloride and sodium nitrate practically did not affect the absorbance of inulinase, probably the metals present in the enzyme extract did not interact with the added salts.

Electrochemical behavior of Cu(II), Zn(II), and Sn(II) ions in simultaneous reduction with thiosulfate ions on a molybdenum electrode

Electrochemical behavior of copper(II), zinc(II), tin(II) in joint reduction with thiosulfate ions on a molybdenum electrode from a citrate solution was studied. It was shown that use of sodium citrate salts as a complexing substance makes it possible to diminish the difference between the reduction potentials of the metals in their joint deposition. The results of an analysis of cyclic voltammetric curves were used to develop a method for electrochemical deposition of a Cu–Zn–Sn–S quaternary compound in a single stage from an aqueous solution on a molybdenum electrode at a constant potential.

Equilibrium Phase Behavior of Aqueous Two-Phase Systems Containing Ethylene Oxide–Propylene Oxide of Different Molecular Weight (2500, 12000) and Sodium Citrate Salt at Various Temperatures and pH

The liquid–liquid equilibrium (LLE) experimental data, including the binodal curve and the tie line of the aqueous two phase systems (ATPS) for two different molecular weights of ethylene oxide–propylene oxide copolymer (2500, 12000) and sodium citrate salt, are presented in two categories: first at different pH values 5, 7, and 8.2 at a constant temperature 25 °C and second at a constant pH of 8.2 with different temperatures of 25 °C, 30 °C, and 40 °C. It is found out that increases in the molecular weight of the polymer, pH, and temperature cause an increase of the two-phase region. Moreover, the experimental binodal data of the considered systems are successfully fitted to the Merchuk equation with significant R2 and low standard deviation.

One-step reverse precipitation synthesis of water-dispersible superparamagnetic magnetite nanoparticles

Hydrophilic functionalization of nanoparticle surface is essential for their biomedical applications. Herein, we report a facile one-step reverse precipitation method to synthesize water-dispersible, biocompatible, and carboxylate-functionalized superparamagnetic magnetite (Fe3O4) nanoparticles with the help of biocompatible sodium citrate salt. Transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), zeta potential measurement, dynamic light scattering (DLS), and superconducting quantum interference device (SQUID) were used to characterize the as-prepared magnetite nanoparticles. The size of the as-prepared magnetite nanoparticles was tuned from 27 ± 3.8 to 4.8 ± 1.9 nm by changing the sodium citrate concentration from 25 to 125 mM. The sodium citrate concentration also influenced the water-dispersible stability of the as-prepared magnetite nanoparticles, which was due to the electrostatic repulsion.

Partitioning of Cephalexin in Aqueous Two-Phase Systems Containing Poly(ethylene glycol) and Sodium Citrate Salt at Different Temperatures

In this study, the partitioning process of cephalexin antibiotic in aqueous two-phase systems (ATPS's) containing poly(ethylene glycol) (PEG) with molar masses of (1500 and 6000) g·mol–1 and sodium citrate salt has been measured. The experimental partition coefficients were measured at three temperatures: (298, 303, and 308) K. The effects of temperature, polymer mass fraction, polymer molar mass, and salt mass fraction on the experimental partition coefficient of cephalexin were also studied. The results showed that the polymer molar mass has a large effect on the partition coefficient and the temperature influence is almost negligible. The experimental data of the partition coefficients of cephalexin in polymer–salt ATPS's were correlated using the equation proposed by Diamond–Hsu.

Toward an Understanding of the Salting-Out Effects in Aqueous Ionic Liquid Solutions: Vapor−Liquid Equilibria, Liquid−Liquid Equilibria, Volumetric, Compressibility, and Conductivity Behavior

The action of particular electrolytes in altering the solution properties of ionic liquids is well documented, although the origin of this effect is not clearly defined. In order to clarify this point, the aim of this work is to obtain further evidence about the salting-out effect produced by the addition of different salts to aqueous solutions of water miscible ionic liquids by evaluating the effect of a large series of salts on the vapor-liquid equilibria, liquid-liquid phase diagram, volumetric, compressibility, and conductometric properties of ionic liquids 1-alkyl-3-methylimidazolium halide ([C(n)mim][X]). In the first part of this work, the experimental measurements of water activity at 298.15 and 308.15 K for aqueous binary and ternary solutions containing 1-alkyl-3-methylimidazolium bromide ([Rmim][Br], R = butyl (C(4)), heptyl (C(7)), and octyl (C(8))), sodium dihydrogen citrate (NaH(2)Cit), disodium hydrogen citrate (Na(2)HCit), and trisodium citrate (Na(3)Cit) are taken using both vapor pressure osmometry (VPO) and improved isopiestic methods. The effect of temperature, charge on the anion of sodium citrate salts, and alkyl chain length of ionic liquids on the vapor-liquid equilibria properties of the investigated systems are studied. The constant water activity lines of all the ternary systems show large negative deviation from the linear isopiestic relation (Zdanovskii-Stokes-Robinson rule) derived using the semi-ideal hydration model, and the vapor pressure depression for a ternary solution is much larger than the sum of those for the corresponding binary solutions with the same molality of the ternary solution. The results have been interpreted in terms of the solute-water and solute-solute interactions. In the second part of this work, the effects of the addition of (NH(4))(3)Cit, K(3)Cit, Na(3)Cit, (NH(4))(2)HPO(4), and (NH(4))(3)PO(4) on the liquid-liquid phase diagram, apparent molar volume, isentropic compressibility, and conductivity of aqueous solutions containing the model ionic liquid 1-butyl-3-methylimidazolium iodide, [C(4)mim][I], are investigated at different temperatures. It was found that there is a relation between the relative concentration of various salts to form two-phase systems with [C(4)mim][I] and apparent molar volume or isentropic compressibility of transfer of [C(4)mim][I] from water to aqueous solutions of the investigated salts.

Effect of simple electrolytes on the thermodynamic properties of room temperature ionic liquids in aqueous solutions

Density, sound velocity and conductivity measurements are carried out on 1-heptyl-3-methylimidazolium bromide ([C 7mim][Br]) in pure water and in aqueous solutions of sodium di-hydrogen citrate, di-sodium hydrogen citrate and tri-sodium citrate over a range of temperatures at atmospheric pressure. The experimental density and sound velocity data are used to calculate the apparent molar volume and isentropic compressibility as a function of temperature and concentration. The effects of temperature and charge on the anion of sodium citrate salts on the apparent molar volume and isentropic compressibility of [C 7mim][Br] are studied. It was found that both of the apparent molar volume and isentropic compressibility of [C 7mim][Br] in aqueous sodium citrate solutions are larger than those in pure water and increase by increasing temperature. The effects of temperature and charge on the anion of sodium citrate salts on the conductivity behavior of the investigated IL solutions are also studied.